nil?

# File activerecord/lib/active_record/relation/query_attribute.rb, line 20
      def nil?
        unless value_before_type_cast.is_a?(StatementCache::Substitute)
          value_before_type_cast.nil? ||
            type.respond_to?(:subtype, true) && value_for_database.nil?
        end
      rescue ::RangeError
      end